Simultaneous and quasi-independent strain and temperature sensor based on microstructured optical fiber

In this paper, a new sensor system for simultaneous and quasi-independent strain and temperature measurements is presented. The interrogation of the sensing head has been carried out by monitoring the FFT phase variations of two of the microstructured optical fiber (MOF) cavity interference frequencies. This method is independent of the signal amplitude and also avoids the need to track the wavelength evolution in the spectrum, which can be a handicap when there are multiple interference frequency components with different sensitivities. The sensor is operated within a range of temperature of 30 degrees C-75 degrees C, and 380 mu epsilon of maximum strain were applied; being the sensitivities achieved of 127.5pm/degrees C and -19.1pm/mu epsilon respectively. Because the system uses an optical interrogator as unique active element, the system presents a cost-effective feature.